package com.roy.KafkaTest.stream;

import java.util.Arrays;
import java.util.Locale;
import java.util.Properties;
import java.util.concurrent.CountDownLatch;

import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.common.serialization.Serdes;
import org.apache.kafka.streams.KafkaStreams;
import org.apache.kafka.streams.StreamsBuilder;
import org.apache.kafka.streams.StreamsConfig;
import org.apache.kafka.streams.kstream.KStream;
import org.apache.kafka.streams.kstream.KTable;
import org.apache.kafka.streams.kstream.Produced;

public class WordCountDemo {
	public static final String INPUT_TOPIC = "streams-plaintext-input";
	public static final String OUTPUT_TOPIC = "streams-wordcount-output";
	private static final String BOOTSTRAP_SERVERS = "172.16.48.10:9092,172.16.48.11:9092,172.16.48.12:9092";
	private static final String TOPIC = "topic1";

	static Properties getStreamsConfig() {
		final Properties props = new Properties();
		props.put(StreamsConfig.APPLICATION_ID_CONFIG, "streams-wordcount");
		props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, BOOTSTRAP_SERVERS);
		props.put(StreamsConfig.CACHE_MAX_BYTES_BUFFERING_CONFIG, 0);
		props.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG,
				Serdes.String().getClass().getName());
		props.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG,
				Serdes.String().getClass().getName());

		// setting offset reset to earliest so that we can re-run the demo code
		// with the same pre-loaded data
		// Note: To re-run the demo, you need to use the offset reset tool:
		// https://cwiki.apache.org/confluence/display/KAFKA/Kafka+Streams+Application+Reset+Tool
		props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
		return props;
	}

	static void createWordCountStream(final StreamsBuilder builder) {
		final KStream<String, String> source = builder.stream(INPUT_TOPIC);

		final KTable<String, Long> counts = source
				.flatMapValues(value -> Arrays.asList(
						value.toLowerCase(Locale.getDefault()).split(" ")))
				.groupBy((key, value) -> value).count();

		// need to override value serde to Long type
		counts.toStream().to(OUTPUT_TOPIC,
				Produced.with(Serdes.String(), Serdes.Long()));
	}

	public static void main(final String[] args) {
		final Properties props = getStreamsConfig();

		final StreamsBuilder builder = new StreamsBuilder();
		createWordCountStream(builder);
		final KafkaStreams streams = new KafkaStreams(builder.build(), props);
		final CountDownLatch latch = new CountDownLatch(1);

		// attach shutdown handler to catch control-c
		Runtime.getRuntime()
				.addShutdownHook(new Thread("streams-wordcount-shutdown-hook") {
					@Override
					public void run() {
						streams.close();
						latch.countDown();
					}
				});

		try {
			streams.start();
			latch.await();
		} catch (final Throwable e) {
			System.exit(1);
		}
		System.exit(0);
	}
}
